Senior U.S. and Saudi officials as well as a senior member of the diplomatic community in Riyadh told NBC News that Saudi Arabia's ambassador to the United States, Prince Bandar bin Sultan, had tendered his resignation to Crown Prince Abdullah in recent days. The resignation appears to be the result of continuing health problems for the 56-year-old envoy.

“You can feel comfortable reporting that,” said the Western diplomat confirming what several Saudi and U.S. officials had told NBC News about the prince's resignation. Bandar is the dean of the Washington diplomatic community. He has been a powerful figure in the United States since being named envoy in September 1983.

A statement released by the Saudi government on Sunday night said Bandar was currently on vacation but that he "continues in his position as ambassador to the United States." The statement neither confirmed nor denied that Bandar had offered his resignation.

But NBC News' Andrea Mitchell, citing a source close to Bandar, reported Bandar has wanted to leave his post for the past 18 months and is awaiting word on what his next government post will be.

Bandar was a key figure in the Saudi decision to permit U.S. bases in Saudi Arabia during the 1991 Gulf War.

There have been persistent reports of Bandar's battle with depression over the last several years. Bandar is also reported to have had problems with over use of antidepressants.

“He has not been as engaged in Washington as he has been in the past,” the diplomat said.

The diplomat and U.S. officials in Washington added that there has been no formal announcement of the resignation because Abdullah has not yet accepted it, but attempts to get Bandar to reconsider have failed.

Had sought intelligence postBandar had wanted to fill the vacant post of intelligence director in Riyadh, and though the post remains open his chances of getting it are slim, said the diplomat. That job would probably go to a more senior member of the royal family, he said.

The diplomat added that the resignation does not appear to be related to the deteriorating health of King Fahd, who remains hospitalized in Riyadh. He said the king's health remains a mystery, but that it is apparently worsening.

Abdullah has been the de facto ruler of Saudi Arabia since Fahd suffered a series of strokes in the 1990s.

“When he went into the hospital, they were saying that he was improving,” the senior diplomat told NBC News. “They have stopped saying that and last week there was a royal wedding he would have been expected to attend. People thought he might leave the hospital then if (he were) able, but he did not.”

Bandar is the son of Prince Sultan, the Saudi defense minister, and has been thought to be the likely successor to Abdullah as both crown prince and prime minister when the king dies and Abdullah takes his place as monarch.

Oil impactBut NBC News' Mitchell reports Saudi officials saying that upon the death of Fahd, Bandar's father will become crown prince. The real succession issue, Mitchell reports, will be who Defense Minister Sultan will designate as his heir apparent.

The sudden nature of the resignation as well as concerns about the king's health will almost certainly lead to an increase in the price of oil on Monday, said oil analyst John Kilduff of FIMAT, one of the world's largest oil traders.

"This will raise suspicions. Guys like this don't suddenly resign," said Kilduff. "That plus the king's health will lead to concerns about the succession in the Kingdom.

"With the price this high, everything matters. The market is extraordinarily sensitive. If the news had come along with an announcement of who is succeeding him, it would have been less of a problem. But bad news in Saudi following the election in Iran will lead to more increases in the price of oil."

Bandar's role in Washington peaked after the Iraqi invasion of Kuwait in 1990. Since the attacks of Sept. 11, 2001, however, Bandar has spent much of his time defending the Saudis' counterterrorism policies.

Mitchell reports that top U.S. officials are aware of Bandar's decision, but there will be no official White House confirmation until the resignation is announced by the Saudis.

NBC News’ Investigative Producer Robert Windrem, Chief Foreign Affairs Correspondent Andrea Mitchell and Nicolla Hewitt of the Today Show contributed to this report.